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Video streaming - is Qos the answer?


We're having problem with a video stream we are distrubuting to a few users. Lately we got a lot of complaits regarding glitches/freezing in the video.

Hardware in 7600's: WS-X6704-10GE


Incomming stream<<--port channel 2G Fiber-->>7600(SUP720)<<--10G fiber-->>7600(RSP720 SVI for video)<<--10G fiber-->> Switch<<-1G RJ45->>PC

- I've checked the interfaces on the 7600's but cant see any errors on the interfaces or output drops on the interfaces(no congestion?)

- We're seeing TX drops from the edge switch to the pc's. Investegating the cause with vendor. But my guess can be buffer problem going from 10G to 1G?

- We have not implemented any Qos on the 7600's however we have enabled qos to prioritize the video vlan on the edge switch.

- Peak traffic between 7600 and edge switch is about 1G(5min average)

- Would enabling QoS on the 7600 and do End to End Qos solve the problem? As far I understand qos will only help if the interface is congested which isn't the case here?

- What would be the best strategy for video streaming? Would the solution be to use the CBWFQ + LLQ  for this kind of traffic or  would LLQ starve the rest of the queue's?

Best Regards

2 Replies 2

Vasilii Mikhailovskii
Rising star
Rising star


Could you provide the qos and port configuration + show interfaces" from edge switch (if not Cisco - try to replace with Cisco for clarity)?

LLQ is good if you limit the amount of traffic it may allocate on the interface.

PS: what is the video stream bandwidth and packet rate?